A 179 isolates of enterobacteriaceae were recently isolated from clinical specimens of patients in
three hospitals in Madinah, Saudi Arabia. Escherichia coli (100) was the commonest organism
followed by Klebsiella pneumoniae (63) and species of Enterobacter (9), whereas others
[Morgan ella morganii(2), Proteus mirabilis(2), Salmonella typhi, Salmonella paratyphi, and
Kl. oxytoca one strain each] were hardly encountered. The MIC for each isolate was determined
by an agar dilution method, against 12 antibiotics.
Against all tested antibiotics, E. coli strains showed the lowest resistance rates, followed by
Kl. pneumoniae strains, whereas those of species of Enterobacter and others exhibited the highest
resistance rates. K. pneumoniae strains, however, showed the highest resistant rates against amikacin